The purpose of the project is to study the biochemistry, morphology, pharmacology and physiology of synaptic transmission and neuronal connections of nerve cells of the mammalian cochlear nucleus. New results have been added to previous findings of the Laboratory to give increasing support for a neurotransmitter role for glutamate/aspartate in the cochlear nucleus: 1. Corresponding to terminals of the auditory nerve, rings of aspartate aminotransferase(AAT)- and glutaminase-like immunoreactivity have been found around cells in the ventral cochlear nuclei. 2. Baclofen, which is believed to block release of excitatory amino acids, strongly suppresses peaks 2, 4 and 5 of the brainstem auditory evoked potential of cat. - New immunocytochemical findings on the distribution of AAT and glutaminase in retina, hippocampus and cerebellum, together with our new findings on the cochlear nucleus and cochlea, indicate that the two enzymes may serve as markers for glutamergic/aspartergic neurons. Studies of the cochlear nucleus, on development in normal mouse, and on structure in normal and reeler mouse, have been published. An important technical innovation has been adapted to a study of postsynaptic densities examined in deep-etched, unfixed slices of guinea pig anteroventral cochlear nucleus.